This is as assumption too, you have a group of people with a lot the same background facing a common enemy. That can level all kinds of differences in a hurry.

Of course it's all assumption.

As are your assumptions that they'd all get along hunky dory.

However, mine is based on an understanding of history. There's still a lot of resentment in Indian Country over broken treaties--a hundred years later. That's not an assumption. That's fact.

I agree with most of what you have said, except the last part. Again you are assuming that those resentments are still festering after another three hundred years and that isn't very realistic. However this is also an assumption based on history.

Perhaps I wasn't clear. I used Indian Country in the US as an example of resentments lasting a very long time. Resentment still exists today over treaties forged & broken a hundred years ago.

In Star Trek, the Federation abandoning the colonists happened within these characters' lifetime. That anger is fresh.